Primordial black hole and wormhole formation by domain walls

By Heling Deng, J. Garriga, A. Vilenkin. 2016

168 citations recorded by the source corpus.

In theories with a broken discrete symmetry, Hubble sized spherical domain walls may spontaneously nucleate during inflation. These objects are subsequently stretched by the inflationary expansion, resulting in a broad distribution of sizes. The fate of the walls after inflation depends on their radius. Walls smaller than a critical radius fall within the cosmological horizon early on and collapse due to their own tension, forming ordinary black holes. But if a wall is large enough, its repulsive gravitational field becomes dominant much before the wall can fall within the cosmological horizon. In this ``supercritical'' case, a wormhole throat develops, connecting the ambient exterior FRW universe with an interior baby universe, where the exponential growth of the wall radius takes place. The wormhole pinches off in a time-scale comparable to its light-crossing time, and black holes are formed at its two mouths. As discussed in previous work, the resulting black hole population has a wide distribution of masses and can have significant astrophysical effects. The mechanism of black hole formation has been previously studied for a dust-dominated universe. Here we investigate the case of a radiation-dominated universe, which is more relevant cosmologically, by using numerical simulations in order to find the initial mass of a black hole as a function of the wall size at the end of inflation. For large supercritical domain walls, this mass nearly saturates the upper bound according to which the black hole cannot be larger than the cosmological horizon. We also find that the subsequent accretion of radiation satisfies a scaling relation, resulting in a mass increase by about a factor of 2.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/45ba4287a6f44e7276a8ff61a6291ae3cdb9a92c

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Citations in the corpus

Gravitational wave signatures of inflationary models from Primordial Black Hole dark matter (2017, methodology): “Various mechanisms for producing PBH have been proposed in the literature, including: the use of a scalar field, coupled to the inflaton, with a symmetry breaking potential, triggering a rapid growth of modes during inflation [2–4]; from the presence of an inflection point in a single-field inflatio”
Primordial Black Holes as Dark Matter: Recent Developments (2020, background): “[130] Heling Deng, Jaume Garriga, and Alexander Vilenkin, “Primordial black hole and wormhole formation by domain walls,” JCAP 1704, 050 (2017), arXiv:1612.”
A Brief Review on Primordial Black Holes as Dark Matter (2021, background): “There are, however, other scenarios which naturally predict a population of PBHs as a result of phase transitions in the early Universe and by the collapse of topological defects (Hawking et al., 1982; Hawking, 1989; Polnarev and Zembowicz, 1991; Garriga et al., 2016; Deng et al., 2017; Deng and Vil”
Primordial black holes as dark matter candidates (2021, background): “Vilenkin and colleagues have argued that bubbles formed during inflation would (depending on their size) form either black holes or baby universes connected to our Universe by wormholes [91,92].”
Clusters of Primordial Black Holes (2018, background): “As has been shown in [63, 64], the walls are not spherical just after formation.”